Pneumococci when suspended in sodium chlorid solution disintegrate and become Gram-negative. The greater the virulence the more rapid the destruction. Non-virulent pneumococci often resist disintegration unless chloroform is added. This process has been proven to be a true autolysis and not due to the action of sodium chlorid in the solution, or to the solubility of the protoplasm of the pneumococcus in water. Several years ago it was shown that the autolytic extract of highly virulent pneumococci in sodium chlorid contained an antiopsonic substance. Similar results have been obtained repeatedly since.
Further studies of the soluble substances and the autolyzed pneumococci are in progress and the following preliminary statements can be made. It seems that by means of autolysis it is possible to separate at least to a large degree the toxic from the non-toxic or antigenic parts of the pneumococcus. The part which goes into solution is the toxic